diff options
Diffstat (limited to 'lib/libc/stdtime/strftime.c')
| -rw-r--r-- | lib/libc/stdtime/strftime.c | 130 |
1 files changed, 76 insertions, 54 deletions
diff --git a/lib/libc/stdtime/strftime.c b/lib/libc/stdtime/strftime.c index 126da85..893b784 100644 --- a/lib/libc/stdtime/strftime.c +++ b/lib/libc/stdtime/strftime.c @@ -17,7 +17,7 @@ #ifdef LIBC_RCS static const char rcsid[] = - "$Id: strftime.c,v 1.17 1997/02/22 15:03:19 peter Exp $"; + "$Id: strftime.c,v 1.18 1997/08/09 15:43:53 joerg Exp $"; #endif #ifndef lint @@ -234,67 +234,89 @@ label: pt = _conv((t->tm_wday == 0) ? 7 : t->tm_wday, "%d", pt, ptlim); continue; - case 'V': - /* - ** From Arnold Robbins' strftime version 3.0: - ** "the week number of the year (the first - ** Monday as the first day of week 1) as a - ** decimal number (01-53). The method for - ** determining the week number is as specified - ** by ISO 8601 (to wit: if the week containing - ** January 1 has four or more days in the new - ** year, then it is week 1, otherwise it is - ** week 53 of the previous year and the next - ** week is week 1)." - ** (ado, 5/24/93) - */ - /* - ** XXX--If January 1 falls on a Friday, - ** January 1-3 are part of week 53 of the - ** previous year. By analogy, if January - ** 1 falls on a Thursday, are December 29-31 - ** of the PREVIOUS year part of week 1??? - ** (ado 5/24/93) - */ - /* - ** You are understood not to expect this. - */ + case 'V': /* ISO 8601 week number */ + case 'G': /* ISO 8601 year (four digits) */ + case 'g': /* ISO 8601 year (two digits) */ +/* +** From Arnold Robbins' strftime version 3.0: "the week number of the +** year (the first Monday as the first day of week 1) as a decimal number +** (01-53)." +** (ado, 1993-05-24) +** +** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn: +** "Week 01 of a year is per definition the first week which has the +** Thursday in this year, which is equivalent to the week which contains +** the fourth day of January. In other words, the first week of a new year +** is the week which has the majority of its days in the new year. Week 01 +** might also contain days from the previous year and the week before week +** 01 of a year is the last week (52 or 53) of the previous year even if +** it contains days from the new year. A week starts with Monday (day 1) +** and ends with Sunday (day 7). For example, the first week of the year +** 1997 lasts from 1996-12-30 to 1997-01-05..." +** (ado, 1996-01-02) +*/ { - int i; + int year; + int yday; + int wday; + int w; - i = (t->tm_yday + 10 - (t->tm_wday ? - (t->tm_wday - 1) : 6)) / 7; - if (i == 0) { + year = t->tm_year + TM_YEAR_BASE; + yday = t->tm_yday; + wday = t->tm_wday; + for ( ; ; ) { + int len; + int bot; + int top; + + len = isleap(year) ? + DAYSPERLYEAR : + DAYSPERNYEAR; /* - ** What day of the week does - ** January 1 fall on? + ** What yday (-3 ... 3) does + ** the ISO year begin on? */ - i = t->tm_wday - - (t->tm_yday - 1); + bot = ((yday + 11 - wday) % + DAYSPERWEEK) - 3; /* - ** Fri Jan 1: 53 - ** Sun Jan 1: 52 - ** Sat Jan 1: 53 if previous - ** year a leap - ** year, else 52 + ** What yday does the NEXT + ** ISO year begin on? */ - if (i == TM_FRIDAY) - i = 53; - else if (i == TM_SUNDAY) - i = 52; - else i = isleap(t->tm_year + - TM_YEAR_BASE) ? - 53 : 52; + top = bot - + (len % DAYSPERWEEK); + if (top < -3) + top += DAYSPERWEEK; + top += len; + if (yday >= top) { + ++year; + w = 1; + break; + } + if (yday >= bot) { + w = 1 + ((yday - bot) / + DAYSPERWEEK); + break; + } + --year; + yday += isleap(year) ? + DAYSPERLYEAR : + DAYSPERNYEAR; + } #ifdef XPG4_1994_04_09 - /* - ** As of 4/9/94, though, - ** XPG4 calls for 53 - ** unconditionally. - */ - i = 53; + if ((w == 52 + && t->tm_mon == TM_JANUARY) + || (w == 1 + && t->tm_mon == TM_DECEMBER)) + w = 53; #endif /* defined XPG4_1994_04_09 */ - } - pt = _conv(i, "%02d", pt, ptlim); + if (*format == 'V') + pt = _conv(w, "%02d", + pt, ptlim); + else if (*format == 'g') { + pt = _conv(year % 100, "%02d", + pt, ptlim); + } else pt = _conv(year, "%04d", + pt, ptlim); } continue; case 'v': |
